Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
A typical image forming apparatus such as a full-color laser printer and a copier includes such as image forming units of four colors, cyan (C), magenta (M), yellow (Y) and black (Bk), and the image forming unit includes a photoreceptor drum and a developing device. Since each of the image forming units includes rotators such as a developing roller arranged in the photoreceptor drum and the developing device, the image forming apparatus includes a drive motor for driving the rotators and a drive transmission device that transmits driving power generated by the drive motor to the rotators.